<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <form action="./type=radio.html">
    <!--
      单选框
       ● name: 值相同的单选框为一组
       ● checked: 默认选中
    -->
    <label><input id="red-input" type="radio" name="color" value="red" checked>红</label>
    <label><input id="green-input" type="radio" name="color" value="green">绿</label>
    <label><input id="blue-input" type="radio" name="color" value="blue">蓝</label>

    <input type="submit">
  </form>
</body>

</html>